I have an '87 Mustang GT convertible, standard tranny and the speedometer stopped working. It appears that the drive gear inside the tranny is FUBAR. Has anyone ever heard of this happening? The car only has 65K on it. I assume that it means that the tranny has to be dropped and opened up to fix the problem. Any thoughts on this?

G36.45

06-13-2005, 18:57

Can't speak to a Mustang specifically but most cars the speedo gear is easily serviceable from the outside.

I would pull it out and then call the dealer. They are usually color coded so the gearing is right to match the rear axle.

The last gear I bought was eons ago and it was like 5-10 bucks but ya never know from a dealer. Are you sure it's the gear bad and you didn't break the speedo cable?

Berlin Kid

06-13-2005, 19:46

Cable is fine. It goes into the cruise control sensor which is attached to the tranny. Pulled the whole assembly out of the tranny. The driven gear looks fine and when I spin it, the speedo moves. That is why I think it is the internal gear that is bad. I was wondering if anyone had experienced something similar and had a "shade tree" fix for this without pulling the tranny.

Ron3

06-13-2005, 20:46

Not postive but I think there is a gear inside and one outside.

Just call a Ford dealer and ask speak to a tranny technician. Ask him.

If your car has the stock transmission it's a T-5. Very simple tranny.

Ron3

imi-pro

06-15-2005, 04:32

If it is the stock tranny, let me know which rear end ratio it is and I may have a couple laying around.

Asha'man

06-15-2005, 14:49

One bolt to get the speed sensor out of the tranny, and IIRC the gear is either press-fit or has a small clip that holds it on.

Once you get the right gear, it's a ten minute job, including raising and lowering the car.

What's your rear gear ratio?

Brian

Berlin Kid

06-15-2005, 20:46

The gear that goes onto the end of the speedo cable is OK...it apparently is the gear inside the tranny on the output shaft.

ALLAN

06-15-2005, 21:56

Did the speedometer needle ever go crazy??
Ususally on the foxbodys the cable just dies. Even if the cable looks ok it can be dead.
I have never had the gear inside the the tranny go bad. You have a t-5 or AOD??

Berlin Kid

06-16-2005, 19:28

Originally posted by ALLAN
Did the speedometer needle ever go crazy??
Ususally on the foxbodys the cable just dies. Even if the cable looks ok it can be dead.
I have never had the gear inside the the tranny go bad. You have a t-5 or AOD??

Speedo just stopped! It is the T-5 tranny and that is what got me as I have never heard of the gear inside the tranny going bad. Guess I need to pull it out and spin it with a drill and see if it registers. I spun it by hand and got some movement and thought that everything was OK. Maybe it is the cable. Thanks all for the input.

indytruckboy

06-17-2005, 05:07

I have been building 5.0s for many years and have never seen a inside gear go bad. ^8

Berlin Kid

06-26-2005, 17:12

Well, I had hope that it was the cable but I pulled the cable, speed transducer, driven gear assembly out of the tranny and connected everything to a drill. At 600rpm, the speedo registered 15mph. So, it appears that everything works so I have to conclude that the drive gear inside the tranny is FUBAR! God I so hoped that it was the cable. Am I missing something here?

If I have to have the tranny dropped to replace the gear, does anyone have any suggestion as to where to take it in Columbus, Ohio?

Thanks for all the input.

spober

06-27-2005, 19:56

my 77 cj5 speedo has never worked.the temp and amp meter works,speedo light works.speedo dont work and odometer dont work.ive changed the cable from g or t box to speedo the gears seem to be working but no go

IHR

06-29-2005, 17:49

I'd keep looking at external issues. If the internal gear went bad, it wouldhave stripped the cable gear as well. Plus the gear on the cable is plastic, the trans gear is metal.